Streptococcus pneumoniae is a gram positive bacterium which is a major cause of invasive infections such as sepsis, meningitis, otitis media and lobar pneumonia (Tuomanen et al. NEJM 322:1280-1284, 1995). Infection by S. pneumoniae remains a significant health threat worldwide. Pneumococci bind avidly to cells of the upper and lower respiratory tract and to endothelial cells present in blood vessels. Like most bacteria, adherence of pneumococci to human cells is achieved by presentation of bacterial surface proteins that bind to eukaryotic cell surface proteins (Cundell, D. & Tuomanen, E. (1994) Microb Pathog 17:361-374). For example, bacteria translocate across cells of the upper respiratory tract and nasopharynx via the polymeric immunoglobulin receptor (pTgR) (Zhang et al. (2000) Cell 102:827-837). Alternatively, when the bacteria are in the blood stream, the pneumococcal bacteria bind to endothelial cells, and the bacteria cross the blood vessel endothelium and enter tissues by binding to and transcytosing with the platelet activating factor (PAF) receptor (Cundell et al. (1995) Nature, 377:435-438).
Current vaccines against S. pneumoniae employ purified carbohydrates of the capsules of up to the 23 most common serotypes of this bacterium, but such vaccines are only 50% protective against pneumonia (Shapiro et al. NJEM 325:1453, 1991) and are not immunogenic under the age of 2. Conjugate vaccines are based on pneumococcal capsular carbohydrates linked to proteins such as diphtheria toxoid or tetanus toxoid. Protection against pneumonia, sepsis, or meningitis for these vaccines is limited to the serotypes present in the formulation, thereby leaving patients unprotected against most of the ninety-two serotypes of this bacterium. Further, vaccines that are protective against both the colonization of pneumococcal bacteria in the nasopharynx, as well, as against entry of pneumococcal bacteria into the bloodstream are needed in the art. Therefore, compositions and methods provided herein fills a long felt need by providing pharmaceutical compositions (e.g., vaccines) for the prevention and treatment of a wide range of serotypes of pneumococcal infections across all age groups.